This workflow uses XNormal to bake normal maps which produces much higher quality shading than previous workflows. The Normal map workflow used in the past will still work, but if you want higher quality shading, this is currently the best workflow to use. It also allows you to use much less supporting geometry since you do not have to fight incorrect shading.
You can use this method one of two ways. One is to give your model a single smoothing group. This will create a very gradient heavy normal map but few seams on UV edges. The other method is to break Smoothing groups along UV seams. This will create a flatter normal map but has some seams on UV edges.
Workflow
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The first step is to make sure your model consists of 1 Smoothing Group. It also helps to triangulate your model using a modifier, that way you do not have to worry about any application changing your triangles.
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When exporting your low-poly model for XNormal using these settings:
The important points are Smoothing Groups, and Tangents & Binormals.
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When loading your low-poly model into XNormal, make sure Use exported normals is enabled.
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After baking your normal map, export your low poly models for Unreal using the SAME FBX settings as before.
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When importing your model into Unreal, select Import Normals:
Results
Here is an example mesh using this method, notice it is far lower poly count than we could use before, there is no supporting chamfers or subdivisions.
